1. Field of the Invention
This invention relates to a nozzle for applying a liquid coating to the edge portions of work pieces. More particularly, the invention relates to an applicator nozzle for coating raw beveled and tenoned edge portions of previously surface coated, decorated panel material such as fiberboard ceiling tiles and panels.
2. Description of the Prior Art
In the formation of decorative fibrous panel board and acoustical ceiling tiles in the past, a prime coat and an intermediate coat of paint were applied to one surface of the material in the course of its manufacture. The material was then cut into the desired lengths and widths. The boards were then tenoned, and bevels formed thereon were ironed and coated with a prime coat of paint. The boards and bevels thereon then received a finishing coat of paint in a separate operation.
It has been recognized in the past that it would be desirable to eliminate the separate operation required for applying the finish coat and be able to obtain a finish-coated work piece directly from the tenoner. However, coating of the beveled edges formed in the tenoning operation has presented a problem in the past. Since fiberboard is porous, the cross-cut surfaces at the beveled portions have loose fibers, fiber ends, and voids which, when painted, have a rough texture and a color which contrasts with the coated face of the work piece. It has also been desirable, due to the dimensional instability of the product, to be able to not only coat the angled bevel edge portion of the work piece, but to also coat part of the remaining edge detail consisting of both a vertical and a horizontal surface since this would eliminate dark lines produced by exposed, unpainted board as the tiles grow and shrink while adjusting to humidity changes after installation. Former methods of coating the edge portions resulted in portions of the edges being skipped and receiving little or no paint. This resulted because the bevels must be coated consistently and accurately at line speeds up to 200 feet per minute, and because the boards may shift slightly as they travel through the tenoner or the board may be warped slightly. Another problem involved in attempting to obtain a finish-coated product directly from the tenoner arises from the fact that since the face of the board would necessarily be finished prior to the bevel coating, complete coverage of the bevel without any noticeable bevel paint on the face is required. Application of coatings of the desired thickness on the edge portions of the work pieces have also been a problem in the past.
Typical of the apparatus used in the past to coat beveled edges of panel boards are those disclosed in U.S. Pat. Nos. 2,165,210 and 2,811,133. In the case of U.S. Pat. No. 2,165,210, a rotatable disk having a circular plane face is inclined at an angle to the horizontal and dips into a supply of coating composition as it rotates, thus transferring a film of the coating composition to a beveled edge surface of a work piece. In U.S. Pat. No. 2,811,133, a similar arrangement is used for picking up the coating material and transferring it to another surface; however, in this case, the coating composition is transferred to a smooth transfer roll which in turn transfers the coating to the beveled edge of the work piece.
U.S. Pat. No. 3,015,301 discloses an apparatus for painting grooves or bevels in the surface of a fiber wall board unit and comprises a vertical paint transfer wheel having a beveled paint carrying and applying peripheral face. A paint spray gun mounted adjacent thereto supplies a uniform coat of paint directly to the peripheral face of the transfer wheel for application to the grooved or beveled portion of the work piece.
U.S. Pat. No. 1,980,552 relates to a paint striping nozzle which is adapted to simultaneously stripe the edge and adjacent side portions of an article. The body portion of the nozzle includes an upper curved nib which protrudes beyond the outlet of a paint discharge duct and extends slightly into the path of the paint which is discharged therethrough. This nib is adapted to engage one surface of an article and hold the outlet of the duct in a predetermined spaced relation from the surface of the article upon which paint is directly sprayed. The nozzle also has a concave nib on the lower portion thereof which extends beyond the extremity of the upper nib and forms a seat for receiving an edge portion of the article or work. This nib has a well which accumulates some of the paint that is discharged from the outlet of the duct and holds it in engagement with the edge portions of the work. In operation, the duct 12 sprays paint directly upon one side surface of the article while the other side surface and edge portion of the article receive paint from the well of the lower nib.
U.S. Pat. No. 3,967,581 relates to an apparatus for applying and smoothing a sealing material under pressure to the edge of particle board. The applicator utilizes a rotary valve means, which may be configured to match the shape of the edge to be coated. The valve has an outlet orifice whose length matches the width of the edge to be coated and may be configured in accordance with the shape thereof. Work piece guides prevent escape of pressurized coating material from the edge portion being coated, and a surface recessed in the amount of the intended thickness of the edge coat is provided adjacent the coating application point and displaced therefrom in the direction of travel of a work piece through the apparatus to limit the amount of material extruded and also to smooth the coating.
None of the prior art disclosures provide a solution to the problems aforementioned.
The coating applicator nozzle of this invention provides a device which will enable finish-coated, beveled edge ceiling boards and panels to be obtained directly from the tenoning operating, thus eliminating a step in the production operation and resulting in a substantial savings of labor, material-handling time, and coating material.